The present invention is directed to a winder. More specifically, the present invention is directed to a method and apparatus for winding viscoelastic material in a manner to reduce distortion of the material after winding of the material onto a roll.
Windup of tire components is an important part of the tire manufacturing process. It has obvious advantages such as in handling, storage, transportation and some tire machines are built to accept only wound components either spooled or rolled. However there are also disadvantages. If the wound component is a contoured component, as opposed to a flat sheet material, the component may become distorted in the winding/storage process. If the component is formed from a low rolling resistance material, the problem can worsen, as such material is very tacky and usually softer.
If distortion occurs when tire components such as belts and carcass materials are wound up, the ends-per-inch count of the wire may change and the material may have to be rejected. In other applications, if the components become crushed, separation from the liner becomes difficult, if not impossible. Calendered material may be distorted and flattened in the center of rolls and sometimes has to be cut away from the liner, wasting expensive liner, time, and material.
All of these problems share a common denominator-distortion due to pressure seen in the windup and storage process.
Center driven winders receive the energy to wind the roll by a motor that rotates a shaft connected to either the shell or the core of the roll. Winding tension is applied by pulling on either the support liner or the component wound on the liner or both. Winding tension control, that is, how the applied tension to the component being wound is varied as the package grows in size during winding, is critical in this type of winding setup.
FIG. 3 illustrates a prior art winding bay 10. A winding platform 1 wheels 14, has a base 16 of either an open square or two side frames upon which are two vertical support frames 18, 20. On each vertical support frame 18, 20 is an axle 22, 24 mounted rotatably on the frame 18, 20, and a roll 26, 28 is mounted on each axle 22, 24. One roll 28 is the windup roll onto which a liner 30 and a stock material 32 are wound. The other roll 26 is the liner let-off roll off,of which the liner 30 is wound when the stock material 32 is wound onto the windup roll 28 and onto which the liner 30 is wound when stock material 32 is removed from the windup roll 28. material 32 is wound onto the windup roll 28 and onto which the liner 30 is wound when stock material 32 is removed from the windup roll 28.
Adjacent to the letoff roll side of the winding platform 12 is the let-off section 34 of the winding bay 10, comprising a plurality of guide rolls. In the illustrated guide mechanism, the liner 30 passes over two top guide rolls 36, 38, through a guide 40 whose function is to spread and de-wrinkle the liner, and over guide rolls 42, 44. The liner 30 then passes under the winding platform 12 and about another pair of rolls 46. After passing about guide roll 48, the liner 30 then contacts the stock material 32 at roll 50 and is wound onto the windup roll 28. The stock material 32 is also guided by rolls 52, 54 before contacting the liner 30.
The primary function of the tension in the liner 30 is to provide proper tracking, guiding, and de-wrinkling during winding. Due to other factors, e.g. misaligned rolls, bearings that are not freely turning, miswound support liners, higher winding tensions are needed to guide and de-wrinkle the liner 30. To provide a high quality wind, one that imparts minimal damage to the wound component, the actual winding tension needed is low.
Thus, the liner 30, during winding and unwinding, is subject to high tension. High winding tension is developed in the letoff section 34 of the winder 10 to provide sufficient tracking and de-wrinkling. This tension is carried into the windup roll 28 and into the stock material 32 being wound. The tension can be thought of as energy that is wound into the roll 28. The dissipation of this energy occurs through the viscoelastic rubber of the stock material 32, causing the stock material 32 to flow, resulting in distortion of the profiles and contours of the component, and sticking to the liner 30.
The present invention is directed to a winding bay and a method of winding that overcomes the limitations of the known winders and winding systems and provides for a high quality wind in the winding bay, minimizing component distortion and stuck-to-liner problems.
Disclosed is a method of winding a viscoelastic material wherein the material and a supporting liner are to be wound onto a roll. The method includes unwinding a liner from a roll, guiding the liner under high tension, guiding the viscoelastic material onto the liner, and winding the viscoelastic material and the supporting liner onto a roll. Before guiding the viscoelastic material onto the liner, the tension in the liner is isolated reduce the tension in the liner.
In one aspect of the disclosed invention, passing the liner through a pair of nip rollers isolates the tension.
Also disclosed is a winding bay for winding a viscoelastic material and a supporting liner onto a roll. The winding bay has a let-off roll, a windup roll, and a plurality of guide rolls to guide the viscoelastic material and the supporting liner. A tension isolation device is located prior to the windup roll to reduce the tension in the liner prior to winding the material and the liner onto the windup roll.
In one aspect of the disclosed invention, the tension isolation device is a pair of nip rollers. In another disclosed aspect, the tension isolation device employs an xe2x80x9csxe2x80x9d wrap or xe2x80x9comegaxe2x80x9d wrap geometry.